Prospective. Randomized study. Published data does not allow for clear determination of the number of patients required for the study. Based on our own experience. The investigators estimate that the average postoperative blood loss is 200ml with a standard deviation of 100ml over 3 days. Based on this assumption. A total number of patients (control + Seamguard groups) of 60 is required if the expected reduction of the mean drainage volume is 100ml and 82 patients for an expected drainage volume reduction of 85ml.